For anyone who really misses XML comment support in VB.NET - check out VBXC - which adds an almost complete implementation to the VB.NET IDE. While it isn't quite stable (it tends to popup error windows now and again almost at random) it is great at what it does with lots of configuration options. My code documentation now looks something like this:
Apart from the coloring (C# differentiates between the XML nodes and their InnerText) it makes me feel right at home. I have just one request though - get rid of the funky licensing disclaimers.
Check it out at http://vbxmldoc.tor-erik.net/